1. Technical Field
The present invention relates to a method and apparatus for controlling a transmission of a vehicle and, more particularly, to a method and apparatus for controlling synchronization of a synchronizer included in a transmission.
2. Description of the Related Art
Generally, power generated from an engine is transferred via a transmission and finally output through wheels with changed revolutions per minute and torque. Transmissions are broadly divided into manual transmissions and automatic transmissions. In the case of a manual transmission, when the driver moves the gearshift to a desired gear step, the shift fork connected with a cable moves a sleeve and engages the same with a desired clutch gear, thereby changing the speed. The manual transmission requires the driver to participate in every operation for changing the speed according to the driving condition, and therefore causing inconvenience to the driver with operations such as manipulation of the clutch.
To address the aforementioned problem, automatic transmissions have recently been widely applied to vehicles. With the automatic transmission, a transmission control unit automatically performs shift to a target gear step according to the driving conditions (the vehicle speed, the degree of opening of the throttle, etc.) of the vehicle. Since the automatic transmission does not require the driver to take a special action to change the speed, it provides convenient driving. However, the automatic transmission causes problems such as degradation of fuel efficiency and power performance.
Recently, an automated manual transmission combining the advantages of the manual transmission and the automatic transmission have been commercialized. With the automated manual transmission, the shift fork is moved with a shift motor connected to an electronic device such as a transmission control unit, rather than being moved by the gearshift connected thereto via a cable.
Such a transmission employs a synchronizer to guide smooth synchronization between the clutch and the gears in changing the speed. The synchronizer, which is intended to guide smooth engagement between gears in changing the speed of the vehicle, synchronizes the rotation speed of the sleeve with the rotation speed of the clutch gear. If a synchronization torque for controlling the synchronizer is excessively high, shock is generated due to inertia of the gears and thus the driving quality is lowered when the speed of the vehicle is changed. If the synchronization torque for controlling the synchronizer is excessively low, the sleeve may fail to engage with the clutch gear.
Accordingly, to accurately perform change of the speed while minimizing shock according to change of the speed, there is a need for a method to determine a proper synchronization torque applied to the synchronizer and more accurately control the synchronizer based on the determined synchronization torque.